Thumb Osteoarthritis Diagnosis and Treatment

Initial Diagnostic Approach

The American Academy of Orthopaedic Surgeons recommends obtaining standard three-view radiographs (posteroanterior, lateral, and oblique) of the hand and wrist as the most appropriate initial imaging study to establish the diagnosis of thumb CMC osteoarthritis, which will likely show joint space narrowing, osteophytes, and subluxation patterns 1
Standard radiographs are essential and sufficient for diagnosis in most cases, and advanced imaging like MRI should not be ordered initially unless radiographs are normal or show only nonspecific findings 1

Consider trigger finger if the swelling is more localized to the flexor tendon sheath and there is catching or locking with finger motion, and consider De Quervain's tenosynovitis if pain and swelling are on the radial side of the wrist 1, 2
Inflammatory arthropathy should also be considered if there are systemic symptoms or involvement of other joints 1

The American College of Rheumatology recommends using a full splint that covers both the thumb base and wrist, as this provides superior pain relief compared to thumb-only splints (NNT = 4 for improving daily activities) 1
Topical NSAIDs are the preferred pharmacological treatment for mild to moderate pain, as they provide equivalent pain relief to oral NSAIDs (effect size 0.77) without increased gastrointestinal complications 1
Activity modification and education about avoiding adverse mechanical factors are recommended as first-line treatment, and heat application may provide symptomatic relief 2

Instruct the patient to perform active finger motion exercises to prevent finger stiffness, which is one of the most functionally disabling adverse effects 3
Exercise regimens involving both range of motion and strengthening exercises are recommended to maintain thumb and finger mobility 2

Oral paracetamol (up to 4g/day) has the best safety profile and should be tried next if topical NSAIDs and splinting are insufficient 1, 2
Oral NSAIDs at the lowest effective dose for the shortest duration may be used if paracetamol fails, with addition of gastroprotection (PPI or H2-blocker) in patients with GI risk factors 1, 2

Intra-articular corticosteroid injection may provide short-term benefit for painful flares, though evidence is limited and effects may not persist beyond one month 1, 2
Intra-articular hyaluronan is an alternative with potentially more prolonged benefit than corticosteroid 1

Surgery should be considered when conservative treatments fail and the patient has marked pain and/or disability affecting quality of life 1, 4
Trapeziectomy alone is the recommended surgical approach, as combination procedures provide no additional benefit but cause significantly more complications (RR 2.12, 95% CI 1.24-3.60) 1

Do not apply ice directly to the skin for acute swelling, as this can cause cold injury; use ice and water surrounded by a damp cloth and limit application to 20-30 minutes 5
Remove rings and other constricting jewelry from the swollen thumb to avoid constriction and damage to the finger 6
Reevaluate patients with unremitting pain during follow-up, as this may indicate complications or alternative diagnoses 3